1. Field of the Invention
The invention relates to a navigation device, comprising a memory for the storage of cartographic dam, a position sensing unit, a control unit, an input unit, a picture memory and a display unit, the control unit being adapted to navigate a user along a predetermined route on the basis of data from the position sensing unit and the cartographic data, the control unit also being adapted to store in the picture memory cartographic data, selected in dependence on a current position determined by the position sensing unit, for display of a relevant map section via the display unit.
The invention also relates to a vehicle comprising such a navigation device.
2. Description of the Related Art
A navigation device of the kind set forth is known from European Patent Application 0 306 088 A1, which corresponds to U.S. Pat. No. 4,996,645, issued Feb. 26, 1991, assigned to the same assignee. The device described therein is capable of displaying a relevant map section, via a display screen, with a name relating to the current route segment, the link between the name displayed and the relevant route segment being emphasized by displaying both items in the same colour. The route itself, determined by entering a starting point and a destination point via the input unit, is not displayed.
German Offenlegungsschrift DE 39 05 493 A1 describes a navigation device where a map section around the current position of the user is displayed. The current position is indicated by a dashed circle with an arrow (see FIG. 3). The route, determined by entering all constituent junctions, is displayed as a heavy line (FIG. 3) or a dashed line (FIG. 2). The clarity of such display is far from ideal.
European Patent Application 0 355 232 A2 describes a navigation device in which a map section around the current position of the user is displayed. The predetermined route is displayed as a heavy line (see FIG. 4 or FIG. 16). The current position is displayed as a triangle (FIG. 1 or FIG. 16). The clarity of display is again far from ideal.
For the use of navigation devices in vehicles participating in traffic, it is of essential importance that information presented to the user by the navigation device does not distract the user too long. When information displayed requires an excessive interpretation time, the navigation device will be useless from a point of view of traffic safety.